A Library of Hydroxamic Acids

Significance

A library of discrete hydroxamic ­acids was prepared from hydroxythiophenol (Marshall) resin. Thus, the reaction of the polymeric ­hydroxythiophenol and various carboxylic acids (3.0 equiv) was carried out with N,N′-diisopropylcarbodiimide (DICC) and 4-dimethyl­aminopyridine (DMAP) at r.t. for 20-30 h to give the corresponding polymeric esters. The esters were treated with 50% aq NH₂OH in dichloromethane at r.t. for 17-24 h to afford the desired hydroxamic acids in 33-100% yield with 74-97% purity (14 examples). When the reaction of the esters was performed in pyridine under similar conditions, a mixture of the hydroxamic acids and carboxylic acids (˜1:1 ratio) was obtained.